For Zeagle 519-BP01S Metal Backplate or the Express Tech Adjustable quick release Tow cable attachments The 519-CS01 Crotch Strap can be used on all Zeagle Backplates and any Zeagle BC (Ranger, Tech, etc.) that has a 1" slot at the bottom of the vest section back. It has a 1" ring to attach to a towing fixture of a DPV (Diver Propulsion Vehicle).